氯代甲基苯基异氰酸酯合成中的热力学计算研究

The application of thermodynamic calculations in synthesis of chloro-methylphenyl isocyanates

通过热力学计算得到6种不同取代位置的氯代甲基苯胺与BTC反应生成氯代甲基苯基异氰酸酯反应在353K时的焓变、熵变、吉布斯自由能变和标准平衡常数,结果显示各反应的吉布斯自由能变在353K下均小于0,而平衡常数K值均大于106,说明反应在353K下可自发进行,且转化率较高,同时还得到6种苯胺的异氰化能力的强弱顺序。通过实验考察了反应物配比,回流时间,回流温度对收率的影响,实验结果显示各种苯胺的异氰化反应的难易程度与热力学计算结果一致。

The enthalpy change,entropy change,Gibbs free energy change and standard equilibrium constant of the reaction of six chloromethyl aniline with BTC at different substitution positions are obtained by thermodynamic calculation.The results show that the Gibbs free energy change of each reaction is less than 0 at 353K,and the standard equilibrium constant K is greater than 10^(6),indicating that the reaction can proceed spontaneously at 353K,And the conversion rate is high;The order of isocyanation ability of 6 kinds of aniline from strong to weak is:2-chloro-4-methylphenyl isocyanate>3-chloro-4-methylphenyl isocyanate>4-chloro-2-methylphenyl isocyanate>5-chloro-2-methylphenyl isocyanate>3-chloro-2-methylphenyl isocyanate>6-chloro-2-methylphenyl isocyanate.The effects of reactant ratio,reflux time and reflux temperature on the yield were investigated.The experiment showed that the difficulty of isocyaniding reaction of various aniline was basically consistent with the theoretical calculation.